Pressed tobacco, although more fermented by virtue of that process, and thus more abounding in properties of tobacco that ever-popular, integration and smoothness, was first made for durability. Sailor could keep it in their pocket; in rope form they could either chew or smoke it. If you buy plug, flake or rope, part of the craft of smoking is to keep it in as intact form as possible, preparing what you need as you go along. Such preparation becomes part of the pipe ritual, relaxing in its own way as smoking.
But the necessity of storing it in jars means that it must fit, so do as you must. When I used to buy pounds of plug, I would dice it all at the beginning, thinking that I'd put all the work in up front so as to get to smoking later. I don't do that now.
Part of the benefit of pressed tobacco is that the longer it stays pressed, the more time the tobacco has to take on the properties, above. Perhaps not very noticeable in the smoking, but hey!, you're smoking the pipe not for its ease but because you adore it. Take the time to add manipulating pressed tobacco to your repertoire and join the ranks of all august pipe smokers! Wear glasses and tweeds and have your picture taken with a stack of leather-bound books.